1. Field of the Invention
The exemplary embodiment(s) of the present invention relates to an optical module. More specifically, the exemplary embodiment(s) of the present invention relates to an optical module with light blocking shield.
2. Description of Related Art
In recent years, with the development of personal mobile devices, various optical devices are incorporated in such personal mobile devices for different application. For example, the light sensor is often used in a smart phone or personal digital assistant (PDA) as a tool to detect object in motion such as a moving finger. To achieve the above effect, the optical sensor needs to receive light reflected by the target object. If there is no light block structure or member to define the angle of incident light for the optical sensor, the optical sensor may be susceptible to other light different from light reflected by the target object, and thus give incorrect detecting result. The more sensitive the optical sensor is, the more serious this problem may become. Similarly, the optical sensor can be used to detect the environmental luminance for displays with automatic brightness control function. If the light sensor receives the ambient light from the environment with the leaking light from the display, deviation may exist in the determination of environmental luminance and the brightness of the display may not be expected.
More particularly, please refer to FIG. 1 which is a schematic cross-section view of a current smart phone design. In FIG. 1, the optical device 20 comprises the aforementioned optical sensor and a die attached to the package substrate 10. (In the following, the optical device includes the die attached thereto) A clear mold 90 is disclosed on the optical device 20 and the package substrate 10 to protect the optical device 10 from damage due to environmental factors such as moisture or oxygen. The optical device 20, the package substrate 10 and the clear mold 90 form a packaged optical sensor as an optical module. The clear mold 90 may be made of transparent encapsulation material commonly used in this art, such as epoxy or silicone. The packaged optical sensor is soldered onto a printed circuit board (PCB) 50 and next to a liquid crystal display 40 enclosed by a case 41. A glass layer 30 and a light blocking member 31 are disposed on the optical device 20. Though the light blocking member 31 can block most ambient light, and the case 41 is opaque and can block most light from the LCD 40, there is still light leakage 1 from the LCD 40 through the gap between the light blocking member 31 and the case 41 and then passing through the clear mold 90. That is, the optical device 20 will rather be affected by light from the LCD 40 than only receive light through the glass layer 30 and the opening defined by the light blocking member 31 as desired.
To address the light leakage problem, some solutions have been provided. For example, please refer to FIG. 2 which is a schematic cross-section view of a smart phone design according to prior art. The difference between the structures in FIGS. 1 and 2 is that the package substrate 10, the clear mold 90, and the optical device 20 are surrounded by a rubber shield 60. Therefore, the light leakage through the gap between the light blocking member 31 and the case 41 is blocked by the rubber shield 60 and cannot reach the optical device 20. Moreover, the rubber shield 60 can be provided as a cushion between the rigid glass layer 30 and other structure, preventing the damage due to contact between the rigid glass layer 30 and other structure.
However, new problems arise from the structure shown in FIG. 2 in practice. Since the rubber shield 60 and other structures including the optical device 20, the clear mold 90, and the package substrate 10 are separately formed. An extra assembly process is required to set the rubber shield 60 to the desired position, such as on the clear mold 90 as shown in FIG. 2, which will increase the production cost. Besides, mismatch between assembling the rubber shield 60 and other structures may occur in the assembly process, so that the production yield may decrease. Assembly gaps may also exist between the light blocking member 31 and the rubber shield 60 due to the mismatch, so that the light leakage problem may not be completely solved by such means.
The information disclosed in the Background of the Invention section is provided only for better understanding of the background of the invention, and should not be taken as an acknowledgment or any form of suggestion that this information forms a prior art that would already be known to a person skilled in the art.